I'd say this is the most realistic with the electricity and such. Just making this theory up on the spot, but I believe that the power plant is abandoned. Actually I'm almost 100 percent certain, as it is filled with wild Pokemon not hiding in grass, no humans, and a fucking beast of legend sitting in it that nobody has noticed. Since it is abandoned, many electric type pokemon such as voltorb and pikachu inhabited the place because they can "feed" off of the electric power. It just seems to me that an electric type Pokemon would be more powerful in a place with all that electricity. Zapdos would be a very powerful electric Pokemon, and would surely be thought of as royalty by the other electric types. Zapdos would benefit from hiding in the power plant because humans are afraid to enter it with all the Pokemon infesting it, it would be able to feed off of the electrical energy, and it would be in a position of power over the rest of the electrical Pokemon.